Question

A man starts walking in east direction 5m then turns towards north 2m and after that turns towards west 3m find the displacement

Answer 1

Well, you need to know the atomic weight of Platinum (Pt) and the number of atoms per mole. The answer to the former is 195.084 g/mole and the latter is 6.023 * 10^23 atoms/mole. Then, multiply everything as shown below:

Number of atoms = (1 g) * (1/195.084 g/mole) * 6.023 * 10^23 atoms/mole

Number of atoms = 3.087 * 10^21 atoms

Note, I’ve included units on everything and you can see that they all cancel except for atoms. Dragging the units along can be a pain but it is a great way to check that they way the numbers are being combined is correct.